/*
** $Id: ltm.c,v 2.38.1.1 2017/04/19 17:39:34 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/

#define ltm_c
#define LUA_CORE

#include "lprefix.h"

#include <string.h>

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"

static const char udatatypename[] = "userdata";

LUAI_DDEF const char* const luaT_typenames_[LUA_TOTALTAGS] = {
    "no value",
    "nil",
    "boolean",
    udatatypename,
    "number",
    "string",
    "table",
    "function",
    udatatypename,
    "thread",
    "proto" /* this last case is used for tests only */
};

void luaT_init(lua_State* L)
{
    static const char* const luaT_eventname[] = {/* ORDER TM */
                                                 "__index", "__newindex", "__gc",  "__mode", "__len",  "__eq",   "__add",    "__sub",
                                                 "__mul",   "__mod",      "__pow", "__div",  "__idiv", "__band", "__bor",    "__bxor",
                                                 "__shl",   "__shr",      "__unm", "__bnot", "__lt",   "__le",   "__concat", "__call"};
    int i;
    for (i = 0; i < TM_N; i++)
    {
        G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
        luaC_fix(L, obj2gco(G(L)->tmname[i])); /* never collect these names */
    }
}

/*
** function to be used with macro "fasttm": optimized for absence of
** tag methods
*/
const TValue* luaT_gettm(Table* events, TMS event, TString* ename)
{
    const TValue* tm = luaH_getshortstr(events, ename);
    lua_assert(event <= TM_EQ);
    if (ttisnil(tm))
    {                                            /* no tag method? */
        events->flags |= cast_byte(1u << event); /* cache this fact */
        return NULL;
    }
    else
        return tm;
}

const TValue* luaT_gettmbyobj(lua_State* L, const TValue* o, TMS event)
{
    Table* mt;
    switch (ttnov(o))
    {
    case LUA_TTABLE:
        mt = hvalue(o)->metatable;
        break;
    case LUA_TUSERDATA:
        mt = uvalue(o)->metatable;
        break;
    default:
        mt = G(L)->mt[ttnov(o)];
    }
    return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}

/*
** Return the name of the type of an object. For tables and userdata
** with metatable, use their '__name' metafield, if present.
*/
const char* luaT_objtypename(lua_State* L, const TValue* o)
{
    Table* mt;
    if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) || (ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL))
    {
        const TValue* name = luaH_getshortstr(mt, luaS_new(L, "__name"));
        if (ttisstring(name))             /* is '__name' a string? */
            return getstr(tsvalue(name)); /* use it as type name */
    }
    return ttypename(ttnov(o)); /* else use standard type name */
}

void luaT_callTM(lua_State* L, const TValue* f, const TValue* p1, const TValue* p2, TValue* p3, int hasres)
{
    ptrdiff_t result = savestack(L, p3);
    StkId func = L->top;
    setobj2s(L, func, f);      /* push function (assume EXTRA_STACK) */
    setobj2s(L, func + 1, p1); /* 1st argument */
    setobj2s(L, func + 2, p2); /* 2nd argument */
    L->top += 3;
    if (!hasres)                   /* no result? 'p3' is third argument */
        setobj2s(L, L->top++, p3); /* 3rd argument */
    /* metamethod may yield only when called from Lua code */
    if (isLua(L->ci))
        luaD_call(L, func, hasres);
    else
        luaD_callnoyield(L, func, hasres);
    if (hasres)
    { /* if has result, move it to its place */
        p3 = restorestack(L, result);
        setobjs2s(L, p3, --L->top);
    }
}

int luaT_callbinTM(lua_State* L, const TValue* p1, const TValue* p2, StkId res, TMS event)
{
    const TValue* tm = luaT_gettmbyobj(L, p1, event); /* try first operand */
    if (ttisnil(tm))
        tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
    if (ttisnil(tm))
        return 0;
    luaT_callTM(L, tm, p1, p2, res, 1);
    return 1;
}

void luaT_trybinTM(lua_State* L, const TValue* p1, const TValue* p2, StkId res, TMS event)
{
    if (!luaT_callbinTM(L, p1, p2, res, event))
    {
        switch (event)
        {
        case TM_CONCAT:
            luaG_concaterror(L, p1, p2);
        /* call never returns, but to avoid warnings: */ /* FALLTHROUGH */
        case TM_BAND:
        case TM_BOR:
        case TM_BXOR:
        case TM_SHL:
        case TM_SHR:
        case TM_BNOT:
        {
            lua_Number dummy;
            if (tonumber(p1, &dummy) && tonumber(p2, &dummy))
                luaG_tointerror(L, p1, p2);
            else
                luaG_opinterror(L, p1, p2, "perform bitwise operation on");
        }
        /* calls never return, but to avoid warnings: */ /* FALLTHROUGH */
        default:
            luaG_opinterror(L, p1, p2, "perform arithmetic on");
        }
    }
}

int luaT_callorderTM(lua_State* L, const TValue* p1, const TValue* p2, TMS event)
{
    if (!luaT_callbinTM(L, p1, p2, L->top, event))
        return -1; /* no metamethod */
    else
        return !l_isfalse(L->top);
}
